This object was made in Tinkercad. Edit it online https://www.tinkercad.com/things/cFewswMF2h6

A welder in my makerspace has a large cabinet of drawers made especially for nuts, bolts, screws, drills and so on. To separate all the different things, the cabinet comes with many small plastic boxes that create a modular sorting system. The basic box is 150 mm square.

Storing drill bits is a bit of a problem as they get longer as the diameter of the drill increases. The smaller pieces are difficult to get out of the bottom of a deep box. A common solution is to make semicircular containers in different sizes and depths.

The boxes are divisions and multiples of the base, so 75x150 is half, 75x75 square is a quarter, 1500x300 is double and so on, as shown in Figure 2.

Picture 3 shows four different versions of the half pipe holders: brown can be up to 146mm long and has two 75mm spaces, green 3 spaces, violet four and the teal 8 spaces which are only ⅓ as deep as the others. But all these fixed length boxes cannot hold bits longer than 146mm. I have many drills that are anywhere between 150 and 350mm in length.

My design for the half pipe drill bit holders dived the 150 mm space evenly, taking into account the thickness of the printed object's walls, which is 2.5 mm.

If I just divide the 150mm in half, the half tubes each have an outer diameter of 75mm and the space taken up by the four wall thicknesses is 10mm in total. This is bigger than necessary. If I make it so that the two halves overlap by 2.5 mm, only 7.5 mm is lost from the thickness of three walls.

The design is in Tinkercad.

And the model has been published on Thingiverse.